Drafting table

ABSTRACT

A drafting table having a tilting board, supported on a desk by columns that are adjustable vertically on the desk. The board may be tilted and locked in any angular position on the upper ends of the columns. A first locking mechanism is provided to lock the columns in any selected vertical position and a second locking mechanism is provided to lock the board at any selected angular position on the columns. The first and second locking mechanisms are so arranged that a single handle actuates both by an improved locking arrangement. The single handle unlocks the angular movement of the board when the handle is moved to a first position and relocks the board and unlocks the columns when the handle is moved to a second position. An energy cell is used in combination with the other apparatus to counterbalance the weight of the board and the columns. A leaf clutch and torsion spring arrangement is used to lock and counterbalance the board in tilting.

ilnited States Patent Hasbrouck et a1.

[54] DRAFTING TABLE [72] Inventors: Gene B. Hasbrouck, Corry; Alan L.

Green, Centerville, both of Pa.

[73] Assignee: Corry Jamestown Corporation, Corry, Pa.

[22] Filed: May 9, 1969 [21] Appl. No.: 823,452

[52] US. Cl. ..108/2, 108/136, 108/148 [51] Int. Cl. ..A47b 27/04 [58]Field of Search ..108/2, 1, 6, 5,10,136, 148;

[451 Aug. 29, 1972 Attorney-Charles L. Lovercheck [57] ABSTRACT Adrafting table having a tilting board, supported on a desk by columnsthat are adjustable vertically on the desk. The board may be tilted andlocked in any angular position on the upper ends of the columns. A firstlocking mechanism is provided to lock the columns in any selectedvertical position and a second locking mechanism is provided to lock theboard at any selected angular position on the columns. The first andsecond locking mechanisms are so arranged that a single handle actuatesboth by an improved locking arrangement. The single handle unlocks theangular movement of the board when the handle is moved to a firstposition and relocks the board and unlocks the columns when the handleis moved to a second position. An energy cell is used in combinationwith the other apparatus to counterbalance the weight of the board andthe columns. A leaf clutch and torsion spring arrangement is used tolock and counterbalance the board in tilting.

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ATTORNEY DRAFTING TABLE DESCRIPTION OF PRIOR ART The drafting tabledisclosed herein constitutes an improvement over US. Pat. No. 3,140,559issued July 14,

1964 to H. N. Grow et al. and over Amthor US. Pat. No. 3,273,517 issuedSept. 20, 1966.

STATEMENT OF THE INVENTION adjustable both in a vertical and in a tiltedrelation to a support.

CROSS REFERENCE TO OTHER PATENTS This application contains claims whichcover a drafting table wherein the drafting board is supported by amechanism which will permit the board to be adjusted in selected tiltedpositions and another mechanism which will permit the board to beadjusted in selected vertical positions. Application, Ser. No. 823,451,contains a similar disclosure and claims drawn to he combination of adrafting table and a control to adjust the table in tilted positions.Application, Ser. No. 823,447, contains a similar disclosure and claimsdrawn to the combination of a drafting table and a control mechanism tocontrol the board in selected vertical positions.

OBJECTS OF THE INVENTION It is an object of the invention to provide animproved drafting board and actuating mechanism.

Another object it to provide a drafting board and control mechanism tocontrol both elevation and tilt functions with a common lever.

Another object is to provide an improved drafting board and control foradjusting and locking the board in both tilted position and elevatedposition to accommodate the individual tastes of a draftsman.

Another object is to provide an improved combination suspension meansfor a drafting board for supporting the board in both tilting andelevation.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an isometric view of thedrafting board according to the invention.

FIG. 2 is an enlarged view of the handle and associated linkage forlocking both the tilting mechanism and the elevation mechanism.

FIG. 3 is a rear view of the drafting board.

F IG. 4 is a view similar to FIG. 3, taken from another direction, withcertain parts broken away.

FIG. 4a is a schematic view of the linkage in locked position for use.

FIG. 4b is a schematic view of the linkage with lever moved to adjustfor tilt.

FIG. 4c, is a schematic view of the linkage with lever in position toadjust the board for elevation.

FIG. 5 is a side view of the desk with parts broken away to better showthe vertical locking mechanism.

FIG. 6 is an enlarged partial cross sectional view showing the energycells used to counterbalance the drafting board in elevation.

FIG. 7 is an enlarged longitudinal cross sectional view through one ofthe legs of the yoke showing the columns which enclose the lockingmechanism for locking the board in vertical position.

FIG. 8 is a cross sectional view taken at right angles to the section ofFIG. 7.

FIG. 9 is a cross sectional view taken on line 99 of FIG. 7.

FIG. 10 is an enlarged cross sectional view showing certain parts of thebrake mechanism.

FIG. 11 and FIGS. '12 and 13 are views of the tilt counterbalance andbrake mechanism for the table.

FIG. 14 is an enlarged view of the board supporting yoke.

DETAILED DESCRIPTION OF THE DRAWINGS The drawings show a drafting boardsupported on a table. The drafting board is adjustable in elevation andmay also be tilted about a horizontal axis.

The drafting board 10 is tiltably connected to the yoke 13 by a hingeconnection made up of plates 17 which are fixed to the yoke 13 by capscrews 73 and support angles 23 which are fixed to the bottom of theboard 10 by fasteners 24 and 24. Tube 59 acts as a hinge pin connectingthe flanges 35 and 35' of support angles 23 and 23 to plates 17 and 17.

The yoke 13 is U-shaped, having the legs 12 and 12 rigidly connectedtogether by transverse member 11. The legs are telescopically supportedin the desk top 18.

The drafting board 10, yoke 13 and desk may be assembled and finished asindicated in FIG. 1 to make an attractive piece of office furniturewhich is very convenient due to the arrangement of all of the controlsincluding lever 37 and crank 100, all disposed at he right hand side ofthe drafting board.

A guard 38 is attached to the board 10 and lever 37 moves laterally inthe guard. The guard 38 has an indent 50 in it in which the lever 37 isdisposed when the table is in the vertical locked mode.

YOKE AND BOARD The board is pivoted to the yoke 13 by pivot tube 5 9.

The cross member 11 and legs 12 and 12' of the yoke 13 may be made ofsheet metal and the legs 12 and cross member 11 are formed into a squaretube configuration. Cross member 11 has a transverse slot 15 extendingfrom one side to the other. The slot 15 provides a path for pickup arm57 to move. Pickup arm 57 is secured to angle bar 47 at points 40 and42. The cross member 11 contains he angle bar 47 which is connected tothe elevation lock. Pickup arm 57 extends through slot 15.

Brackets 17 and 17' are fixed to the ends of cross member 11 by capscrews 73 and 73 which extend through spacer bushings 56 and 56' and arefixed to the cross member 11 of the yoke at each side at he upper endsof legs 12 and 12'. Each bracket 17 and 17' has a hole in it whichreceives pivot tube 59.

Drafting board 10 has two support angles 23 and 23' fixed to it. Theangles 23 and 23' have horizontal flanges 36 and 36 respectively fixedto the board 10 and vertical flanges 35 and 35 respectively by fasteners24 and 24' which extend in a plane parallel to the platelike brackets 17and 17'. Flanges 35 and 35 each have hole which is aligned with a holein brackets 17 and 17'. Pivot tube 59 extends through the holes inbrackets 17 and 17 and through the holes in flanges 35 and 35' and forma hinge pin for the board to tilt about. The drafting board 10 is thustiltably supported on the yoke 13.

TILT COUNTERBALANCE The left hand end of pivot tube 59 is welded tovertical flange 35' of support angle 23'. The right hand end of tube 59has a nut 55' threadably received on it. Thus the flanges 35 and 35' maybe held from spreading apart and moving away from each other by pivottube 59. The support angles 23 and 23 may be adjusted toward and awayfrom each other by loosening the fasteners 24 by which the supportangles 23 and 23' are held to board 10. Slots 64 will then allow supportangles 23 and 23' to be moved laterally on board 10 to adjust thesupport angles relative to the two groups of brake leaves 75 and 75Torsion bar 16 extends through pivot tube 59 and limit plate 94 is fixedto the left hand end of bar 16. Torsion lever 101 is fixed to the righthand end of torsion bar 16. Stop bracket 95 is welded to the verticalflange 35 at the left hand end of the board. A cap 89 is disposed inhole 91 in stop bracket 95. When the board 10 is tilted, lever 94rotates with torsion bar 16 until it engages the stop bar. When thelever 94 engages the stop bar, further rotation of the left hand end ofthe torsion bar 16 relative to board 10 is stopped.

The right hand end of torsion bar 16 protrudes from the right hand endof the tube 59 and adjusting lever 101 is fixed to the right hand end oftorsion bar 16. Two paced studs 103 extend through plates 102 andthreadably engage plate 85 which is fixed to vertical flange 35. Thus,when the drafting board is swung toward a horizontal position, the righthand end of torsion bar 16 is forced by lever 101 to rotate with theboard 10. The left hand end of torsion bar 16, however, is held fromrotating by limit plate '94 and the stop bar. Lever 101 is sandwichedbetween plates 102 and 102'. Thus tilting the board twists torsion bar16 and a counterbalancing force tending to urge the board 10 to avertical position results. The counterbalance force can be increased byloosening studs 103 and rotating lever 101 clockwise, in the directionof the arrow (FIG. 12) and relocking the lever 101 in its new positionby retightening studs 103. Lock washer 104 will prevent lever 101 fromslipping. By thus adjusting the torsional force by means of lever 101,the board may be precisely counterbalanced so that very little manualforce is required to move the board 10 to difl'erent tilted positionswhen the tilt lock is released.

TILT-LOCKING The board 10 may be positively locked in any tiltedposition by the efficient locking mechanism which is provided.

The locking mechanism is made up of two groups of brake leaves 75 and75', one of the groups of brake leaves disposed at each side of thetable. The brake leaves are squeezed together by a toggle linkage toform a positive lock for the board.

The group of brake leaves 75 is provided at the right hand side of thetable. Group 75 is provided at the left hand side of the table. Group 75is made up of first leaves 77 which have spaced holes which looselyreceive pins 74 that are fixed to vertical flange 35 at the right handside of the table. Angle brackets 66 are fixed to horizontal flange 36of angle 23 and the brake leaves 77 are received betweenangle brackets66 and flanges 35. Angle bracket 66 is attached to flange 36'. Secondleaves 78 are interleaved between first leaves 77 and are freelyreceived on spacers 56 which are fixed to yoke 13 by cap screws 73.Second group 75 of brake leaves are made up of first leaves 77' andsecond leaves 78' interleaved with each other in. the same manner as theleaves 77 and 78 of the first group 75. Leaves 77, 78, 77' and 78' havea large hole through which pivot tube 59 extends. Bracket 17' is fixedto legs 12' of yoke 13 and is supported by cap screws 73'. Cap screws73' are threadably received in leg 12'. Similar capscrews attach bracket17 to leg 12.

Leaves 77 and 73, as well as leaves 77 and 78', are free to float ontheir respective pins 74, 74' and sleeves 56 and 56' supported on capscrews 73 and 73' at each side of the table.

Square tubes 72 and 76 are telescopically received on pivot tube 59.Washers 71 and 71' are supported between the outer ends of square tubes72 and 76 and the respective groups 75 and 75' of brake leaves. Linksare pivoted to the square tube 72 at 51. Crank links 68 are pivoted tosquare tube 76 at 53. Lever 73 is fixed to links 68. Links 68 arepivoted to links 70 at 52. Thus when lever 37 is in the position A shownin FIG. 4, the square tubes 72 and 76 will be moved outward from eachother to their extreme outward position and they will exert a maximumclamping force on the brake leaves in groups 75 and 75', forcing theirleaves into frictional engagement with each other in the group. Thisforce may be increased by adjusting support angles 23 inward toward eachother by sliding the support angles 23 and 23 on fasteners 24 in lots 64and by loosening studs 103 and readjusting nut 55, then retighteningstuds 103.

ELEVATION LOCK The drafting board is locked against movement inelevation as well as against tilting by the lever 37. When lever 37 ismoved from position A to position B (FIGS.

'2 and 4), the distance between points 53 and 51 is decreased and squaretubes 72 and 76 move toward each other and release their force on thetwo groups of brake leaves 75 and 75' thus allowing the board 10 totilt.

lt will be seen that sleeve 79 is telescopically received on tube 76,and links 69 are pivoted to tubes '79 at 55 as well as to link 68 at54'. Flange 58 is fixed to sleeve 79. Therefore, when lever 37 is movedtoward position C, sleeve 79 is moved toward the left and pickup armflange 58 engages pickup lever 57. Further movement of lever 37 willcause a force by link 69 on flange 58 pickup 57. An equal and oppositereaction force will be exerted by link 70 on square sleeve 72. Thereaction force will relock the group of brake plates 75 at the righthand side thereby relocking the board 10 against tilting. However, thegroup of brake plates 7 5' at the left hand side will remain unlocked.The force exerted by the single group of locked plates 75 at the rightside of the table is sufficient to retain the board 10 in its tiltedposition while the operator is adjusting the board in elevation.

When lever 37 is in position C the elevation locking mechanism will beunlocked. This is accomplished by the force on pickup link 57 which isconnected to the vertical locking mechanism through bar 47 and bellcranks 67 and 67 The elevation lock mechanism is basically a helicalspring 49 in each leg 12 of yoke 13 which grips the vertically extendingrods 46 and 46' which are fixed to the table base.

The legs 12 may be formed of sheet metal or other suitable material. Thelegs each have a top wall 20, side walls 21 and 26, and front and rearwalls 27 and 28. The legs of the yoke 13 are slidable up and down in thetable side panels 14. The vertically extending tracks 29 are supportedat each side of the table and they provide guides for movement of legs12. The tracks are in the form of a channel having each side leg of thechannel bent to form grooves 34 for a wheel 30 and 31. Wheels 30 and 31are fixed to the lower ends of legs 12 to roll in the grooves when boardis moved in elevation.

Each of side panels 14 has a bottom 33 which turns inward from sides 14.Lock rod 46 is fixed to plates 60 which is attached to bottom 33 bymeans of screws 61. Bracket 65 is in the form of a plate fixed to sidewall 21 of leg 12 by screws 44'. Both the upper end and the lower end ofbracket 65 are turned outward and the lower end has a hole in it throughwhich rod 46 extends. Rock lever 48 is in the form of a plate pivoted tobracket 65 by rivet 48. The helical spring 49 has eyelets formed on itsends which receive screws 62 and 51. The rod 46 passes through the helixof spring 49.

The upper end of compression spring 44 rests against the upper end 65'of bracket 65. The lower end of spring 44 rests against lever 48 urginglever 48 to pivot on rivet 48' thereby twisting spring 49 and causingspring 49 to grip rod 46. Spring hairpin link 45 has its lower endhooked under the lower end of spring 44 and is attached to connectingbar 64 by rivet 64'. Spring 44 is a helical compression spring. Hairpinlink 45 extends through the inside of the helical spring 44 and pilotsit thereby holding it in position.

Bell cranks 67 and 67' are pivoted to cross member 11 at 39 and 39'respectively. Bell cranks 67 are also pivoted to bars 64 and 64 at 43and 43 and pivoted to angle bar 47 at 41 and 43 respectively.

Thus when lever 37 is moved to position C, flange 58 acting throughpickup 57 will move angle bar 47 to the left rotating bell cranks 67about their pivots 39 and lifting hairpin links 45. This will compressspring 44 and allow lever 48 to freely rotate and rotate spring 49 sothat they can freely slide on rods 46. Thus the yoke 13 with board 10 onit can freely move up or down.

ELEVATION COUNTERBALANCE The weight of the drafting board 10 and yoke 13is counterbalanced in elevation by the mechanism made up to two energycells, one located at each side of the table. (FIGS. 1, 4 and 6). Eachenergy cell is basically an outer drum 90 and an inner shaft .82 with aclock spring wrapped on the shaft and attached to the drum. The twoenergy cells, one at each side of the table, each have a drum 90 with anouter circumferential flange 97 to which an end of a cable 83 isattached. The lower end of each cable is attached to an eyebolt 84 inturn connected to a leg 12 of the yoke. Drums 90 are connected togetherto rotate as one by outer tube 92 which has notches in its end whichreceive lugs 92 on the inner ends of drums 90. Thus the drums 98 arerestrained to rotate in unison by outer tube 92 and cables 83 arewrapped on drums 90 as the table is raised.

Inner tube 93 is attached to the spool connected to shaft 82 on which aclock spring is wound. The outer end of the clock spring is attached tothe inner periphery of the drum 90. The spring may be tightened and thusmore counterbalancing force applied to the yoke by tightening thesprings.

Shaft 82 of the energy cell at the right hand side of the table isconnected through inner tube 93 to the inner shaft in theenergy cells atthe left hand side of the table. By rotating crank 100 and its worm 96,worm gear 81 is rotated and by it, shaft 82 and the inner shafts of bothenergy cells and the tension on the spring inside the energy cells isthereby increased.

The board 10 and the yoke 13 can be levelled with respect to the base byadjusting the length of cables 83. This can be accomplished by adjustingthe nuts on eye bolts I It will be noted that handle 37, as well ascrank 100, are both located at the right hand side of the table so thatthe operator has convenient access to them with his right hand. Byadjusting the tension on the energy cells, the drafting board and yokecan be counterbalanced so that it can be moved to the desired heightwith a minimum of manual effort. By adjusting lever 101, the torsionalforce exerted by the torsion bar can be adjusted so that the board maybe tilted with a minimum effort when the handle 37 is in position B. Bymoving lever 37 to position C into indent 50, the board is lockedagainst tilting but is free to be moved vertically. Since both verticaland horizontal locks are actu ated by a single lever 37, the operatormay operate the lever 37 with one hand at the same time have the otherhand free to move the board to desired position.

FIGS. 4a, 4b and 4c are schematic views that show the relative positionsof the locking mechanisms and associated linkages which look and unlockthe board 10 so that it may be tilted and adjusted to the desiredposition and elevation.

The part of bellcrank 68 between pivot 52 and 53 may be considered to bea first link, link as a second link, and link 69 as a third link. Thetilt lock may be considered to be a first lock, the elevation lock maybe considered to be the second lock.

When the operator desires to adjust the board 10 to a different tiltedposition, he moves the lever 37 to position B. In position B, the lever37 moves the linkages to relock the brake on the right hand side of thetable and unlock the tilt lock. in position B, pivots 51 and 53 movetoward each other, causing the tubes 72 and 76 to move toward each otherand away from brakes and 75'. This causes the brakes to release andallows the table to tilt. However, at this point, the elevation lockremains locked.

When the lever 37 is moved toward position C, the flange 58 engages thepickup 57. Further movement of the lever 37 brings the member 71 intoengagement withthe brake 75 exerting a force which has a reaction onpickup 57. This moves the link 47 to the left and rotates the bellcranks67 about their pivot point which causes the links 64 and 64 to be liftedthereby lifting the links 43 about their pivot 38' and against the forceof the compression spring 44. Thus the spring 49 releases its grip onthe column 46 and the table may be adjusted in elevation while itstilting function is relocked. When the table is adjusted to the positiondesired, the operator will return the lever 37 to the A position, thusrelocking the table against tilting and allowing the spring 44 to swingthe lever 48 to the position to cause the spring 49 to again grip thecolumn 46.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. In combination a locking mechanism for a drafting board,

said drafting board being mounted on a support,

a means to adjust said board for tilting on said support and means toadjust said board vertically on said support,

said means to adjust said board for tilting comprising first lock meansto lock said drafting board on said support in selected position againsttilting,

second lock means to lock said drafting board in selected verticalposition,

and a single handle connected to both said locking means for actuatingboth said locking means by movement of said handle,

said first lock means and said second lock means being locked when saidhandle is in a first position,

said first lock means being unlocked and said second lock means beinglocked when said handle is moved to a second position,

said first lock means being relocked and said second lock means beingunlocked when said handle is in a third position.

2. The combination recited in claim 1 wherein said drafting board issupported on a first leg and a second leg,

transverse means fixing said legs together at their upper ends,

and counterbalance means for counterbalancing said drafting board invertical position.

3. The combination recited in claim lwherein said counterbalance meanscomprises an energy cell at one side of said drafting board,

said energy cell having an outer drum,

a shaft and a spring connecting said shaft to said drum,

and cable means connected to said legs and to said drum,

4. A drafting table comprising a support structure,

a drafting board,

first means attaching said drafting board to said support structure fortilting,

second means connecting said drafting board to said support structurefor vertical movement whereby said drafting board can be moved up anddown,

first locking means to lock said drafting board against tilting andsecond locking means to lock said drafting board against verticalmovement,

and an actuating member connected to said first locking means and tosaid second locking means for actuating both said locking means lockingsaid drafting board against tilting and against vertical movement,

said actuating member is movable to a first position to lock saiddrafting board against both tilting and vertical movement,

said actuating member is movable to a second position to unlock saidtilting movement and to lock said vertical movement and to a thirdposition to lock said drafting board against tilting and unlock saidboard for vertical movement.

5. A drafting table comprising a supporting structure, a pair of spacedlegs comprising a yoke mounted for vertical movement on said supportingstructure,

a drafting board,

pivot means on each said leg supporting said drafting board on saidyoke,

said first lock means comprising two interleaved groups of brake plates,

means securing the plates of one of said groups of said plates to saiddrafting board,

means securing the other plates of said group of said plates to theupper end of one of said legs,

a pivot tube extending through said groups of brake plates,

and actuating means for pressing said brake plates of both said groupstogether in tight frictional engagement to hold said drafting board inselected pivotal position relative to said leg,

said actuating means comprising a toggle linkage, in-

cluding a first link and a second link, a third link attached to saidtoggle linkage,

said third link having means thereon connected to an elevation lock toactuate a second lock means to lock said legs against vertical movement,

a torsion rod extending through said pivot tube, one end of said torsionrod being fixed to said base, the other end of said torsion rod beingfixed to said drafting board,

said first lock means and said second lock means being locked when saidactuating means is in a first position,

said first lock being unlocked and said second lock being locked whensaid actuating means is in a second position said first lock beingrelocked and said second lock being unlocked when said actuating meansis in a third position.

6. The drafting board recited in claim 5 wherein said yoke comprises atransverse member,

a first leg and a second fixed to said transverse member, I

said legs being telescopically and slidably received in said base toraise and lower said board,

an elevation lock means to lock said legs in selected elevated position,

said actuating means comprising an angle bar in said transverse memberof said yoke,

the outer ends of said transverse member being attached to said lockingmeans,

a pickup arm fixed to said bar,

and means connected to said links to engage said pickup arm to actuatesaid elevation lock.

7. A drafting board comprising a support member,

a first leg and a second leg spaced from each other, said spaced legsslidably supported on said support for vertical movement thereon,

a drafting board,

said drafting board being attached to an upper portion of said legs fortilting movement thereon,

two spaced support angle members attached to the lower side of saiddrafting board,

one flange of each said support angle extending generally perpendicularto said drafting board,

two groups of plates made up of a plurality of first brake plates andsecond brake plates disposed in parallel planes, one said group beingdisposed adjacent each said support angle,

first spaced pins fixed to said vertical flanges and extending throughholes in said first brake plates,

two second groups of brake plates made up of first brake plates andsecond brake plates,

second pins fixed to said legs, said second pins extending through holesin said second brake plates,

a first bracket fixed to said first leg and a second bracket fixed tosaid second leg,

a tube extending through said brackets through said support angles andthrough both said first brake plates and through said second brakeplates whereby said drafting board is tiltably supported on said legs,

said tube extending through said first plates and said second plates,

a first brake engaging member slidably supported on said tube andengaging said first brake plates,

a second brake engaging member slidably supported on said tube andengaging said second brake plates,

a lever,

a first link having its first end pivoted to said lever at a first pivotpoint and having its second end pivoted to said first brake engagingmember,

said lever being swingably attached at a third pivot point to saidsecond brake engaging member,

said first pivot point and said second pivot point being spaced fromeach other,

said lever being adapted to be swung from a first position to a secondposition whereby said first brake engaging means and said second brakeengaging means are forced away from each other and said first brakeplates and said second brake plates are squeezed together locking saiddrafting board against tilting,

said lever being swingable to a second position where said first pivotmoves between said second pivot and said third pivot to a secondposition on the opposite side of said line through said second pivot andsaid third pivot whereby said first brake engaging member and saidsecond brake engaging member are moved toward each other and said brakeplates are allowed to move away from each other,

said lever being movable to a third position,

second locking means for locking said columns in adjusted verticalpositions,

said second locking means having a member engagable by second lockactuating means on said lever whereby said second locking means isactuated when said lever is moved to said third position.

8. In combination, a drafting board and a support,

first means supporting said drafting board for tilting on said support,

second means supporting said drafting board for movement in elevation,

first lock means for locking said drafting board against tilting on saidsupport,

second locking means for locking said drafting board against movement inelevation,

actuating means for said first lock means comprising a first link, asecond link pivotally connected to said first link forming a togglelinkage,

said first link and said second link being connected to said first lockmeans at their distal ends,

a handle attached to said first link,

a third link, having a first end and a second end, said third link beingconnected to said first link at its said first end and connecting meansconnecting the said second end of said third link to said second lockmeans,

said third link being connected to said first link at a position betweenthe connection of said second link to said first link and said handle.

9. The combination recited in claim 8 wherein said first locking meanscomprises interleaved plates at each side of said drafting board,

and said first link and said second link are adapted to force saidplates together in frictional engagement with each other.

10. The combination recited in claim 8 wherein said second locking meanscomprises two spaced vertical extending rods fixed to said support,

two helical springs, one said helical spring disposed around each saidrod,

two rock plates rotatably supported on said means supporting saiddrafting board for tilting,

each said helical spring having two ends, said two ends of each saidspring being fixed to one of said rock plates,

said rock plates being connected to said connecting means.

11. The combination recited in claim 9 wherein said second locking meanscomprises two spaced vertical extending rods fixed to said support,

two helical springs, one said helical spring disposed around each saidrod,

two rock plates rotatably supported on said means supporting saiddrafting board for tilting,

each said helical spring having two ends, said two ends of each saidspring being fixed to one of said rock plates,

said rock plates being connected to said connecting means.

12. The combination recited in claim 10 wherein said connecting meanscomprises two bell cranks fixed to said support,

vertically extending means connecting said bell cranks to said rockplates,

a pickup member connected to said bell cranks,

and means connected to said third link adapted to engage said pickupmember to move said bell cranks and thereby move said rock levers tomove said helical springs out of binding engagement with said rods.

13. The combination recited in claim 12 wherein said means supportingsaid drafting board on said support comprises a tubular member supportedon said support,

said first lock means comprising a first tubular member and a secondtubular member telescopically supported on said tubular member, saidfirst and second tubular members comprising said first lock means andsaid second lock means,

and a third tubular member slidably supported on said second tubularmember, said third tubular member engaging said pickup member.

14. The combination recited in claim 13 wherein a compression spring isdisposed in engagement with said rock levers urging said rock levers tourge said helical springs to bind on each said rod,

said compression spring being adapted to exert a force on said thirdlink when said lever is moved to a position to move said first lockingmeans toward 15 each other whereby said first link and said third linkco-act to lock said first locking means.

15. In combination, a drafting board and a support with a lockingmechanism for locking two relatively swingable members togethercomprising two spaced first members and two spaced second members, saidfirst members being fixed to a drafting board, said second members beingfixed to said support,

a first tubular member extending through said first members and saidsecond members swingably connecting said first members and said secondmembers together,

a first group of brake leaves and a second group of brake leaves, saidgroups of brake leaves each being made up of a plurality of first brakeleaves and second brake leaves, said first brake leaves being looselyreceived on spaced first pins on said first members, said second brakeleaves being loosely received on second pins on said second members,said tubular member extending through a hole in each of said brakeleaves thereby connecting said first brake leaves to said second brakeleaves,

a first square tube telescopically received on said first tubular memberand disposed adjacent said first group of brake leaves,

a second square tube telescopicaliy received on said first tubularmember and disposed adjacent said second group of brake leaves,

means on said first square tube engaging said first brake leaves,

means on said second square tube engaging said second brake leaves,

a crank link pivoted at one end to means on said first square tube, afirst link pivoted at one end to said second square tube and to saidcrank link,

said crank link being swingable to urge said brake leaves together tohold said first brake leaves in frictional engagement with each other,

a third square tube slidably supported on said second square tube,

a second link pivotably connected to said crank link at its first endand to said third square tube at its second end,

said first link being pivoted to said crank link between the pivotalconnection of said crank link to said second tube and the pivotalconnection of said second link, 65

said third square tube having means thereon adapted to engage a pickupmember,

a handle fixed to said crank link,

said handle being swingable to a first position urging said first squaretube and said second square tube from each other whereby said brakeleaves of said first group and said brake leaves of said second groupare each urged into frictional engagement with each other,

said handle being swingable to a second position whereby said leaves ofsaid first group and said brake leaves of said second group can eachswing relative to the other,

said handle being swingable to a third position whereby said second linkforces said third square tube into engagement with said pickup memberand a force is thereby exerted between said third tubular member andsaid first tubular member forcing said brake leaves of said firsttubular member into frictional engagement.

16. The combination recited in claim 15 wherein a 20 torsion bar istelescopically received in said first tubular member,

said torsion bar has a first end and a second end,

said first end of said torsion bar is fixed to said support,

said second end of said torsion bar is fixed to said drafting board.

17. The combination recited in claim 16 wherein said second end of saidtorsion bar has adjusting means connecting it to said drafting boardwhereby the torsional 30 force counterbalancing said drafting board maybe adjusted.

18. The combination recited in claim 17 wherein said support comprises ayoke having atransverse member and two spaced vertically extending legs,

a disk member slidably supporting said legs,

a locking means for holding said yoke in predetermined verticalposition,

a laterally extending bar on said transverse member,

a first bell crank and a second bell crank attached to each end of saidtransverse member,

a locking member on each said leg and attached to each said bell crank,

said pickup member being attached to said transverse bar.

19. The drafting table recited in claim 1 wherein said drafting board isattached to a yoke having a pair of spaced legs mounted on saidsupporting structure,

pivot means on each said leg supporting said drafting board on saidyoke,

said means to adjust said board for tilting comprising a first group ofbrake plates and a second group of brake plates interleaved with saidfirst group of brake plates,

means securing the plates of said first group of said plates to saiddrafting board,

means securing the plates of said second group of said plates to theupper end of one of said legs,

a pivot tube extending through said groups of brake plates,

said handle comprising actuating means for pressing said brake plates ofboth said groups together in tight frictional engagement with each otherto hold said drafting board in selected pivotal position relative tosaid leg,

said actuating means further comprising a toggle linkage, including afirst link swingably connected torsion rod extending through said pivottube, one end of said torsion rod being fixed to said yoke, the otherend of said torsion rod being fixed to said drafting board.

21. The drafting board recited in claim 19 wherein said pivot meansfurther comprises spaced platelike brackets on said yoke, one at eachside thereof,

a first flange and a second flange spaced from each other and fixed tosaid board and disposed in planes generally parallel to said brackets,

said first group of brake plates disposed ad-jacent said first flange,

said second group of brakes plates disposed adjacent said second flange,

said tube having a first end and a second end extending through saidbrackets and through said flanges and through said first group of brakeplates and through said second group of brake plates,

said first end of said tube having a nut thereon abutting the outsidesurface of said first flange,

the said second end of said tube being fixed to said second flange.

22. The drafting board recited in claim 21 wherein said first flange hasa first horizontal flange fixed thereto and said second flange has asecond horizontal flange fixed thereto,

said horizontal flanges each having two laterally extending slotstherein,

fastening means in said slots engaging said board holding said board tosaid horizontal flanges whereby said first and said second flanges maybe adjusted toward and away from each other to adjust the outwardmovement of said brake leaves.

23. The drafting board recited in claim 22 wherein said actuating meansfurther comprises a first outside sleeve telescopically supported onsaid tube adjacent said first group of brake leaves,

a second outside sleeve telescopically supported on said tube adjacentsaid second group of brake leaves,

said means supporting said first link and said second link on said pivottube comprises said first link pivotally attached to said first outsidesleeve,

said second link pivotally attached to said second outside sleeve,

said links being swingably connected together and handle means fixed toone said link.

24. The drafting board recited in claim 21 wherein a torsion bar extendsthrough said first tube,

said torsion bar having a first end and a second end,

means fixing a first end of said torsion bar against rotation relativeto said first flange,

means fixing said second end of said torsion bar against rotationrelative to said second bracket whereby said torsion bar is twisted whensaid board is tilted from a horizontal position.

25. The combination recited in claim 1 wherein said means to adjust saidboard comprises a first leg and a second leg spaced from each other,said spaced legs slidably supported on said support for verticalmovement thereon,

said drafting board being attached to an upper portion of said legs fortilting movement thereon,

a first support angle and a second support angle spaced from each otherand attached to the lower side of said drafting board,

one flange of each said support angle extending generally perpendicularto said drafting board,

a first group of plates made up of a plurality of first brake plates anda plurality of second brake plates,

a second group of brake plates made up of a plurality of third brakeplates and a plurality of fourth brake plates disposed in parallelplanes, one said group being disposed adjacent each said support angle,

first spaced pins fixed to said vertical flanges and extending throughholes in said first brake leaves,

a first bracket fixed to said first leg and a second bracket fixed tosaid second leg,

second pins fixed to said brackets, said second pins extending throughholes in said second brake leaves,

a tube extending through said brackets through said support angles andthrough both said first brake leaves and through said second brakeleaves whereby said drafting board is tiltably supported on said legs,

a first brake engaging member slidably supported on said tube andengaging said first group of brake leaves,

a second brake engaging member slidably supported on said tube andengaging said second group of brake leaves,

a lever,

a first link having its first end pivoted to said lever at a first pivotpoint and having its second end pivoted to said first brake engagingmember at a second pivot point,

said lever being swingably attached at a third pivot point to saidsecond brake engaging member,

said first pivot point and said second pivot point being spaced fromeach other,

said lever being adapted to be swung from a first position to a secondposition whereby said first brake engaging means and said second brakeengaging means are forced away from each other and said first brakeleaves and said second brake leaves are squeezed together locking saiddrafting board against tilting,

said lever being swingable to a second position where said first pivotmoves between said second pivot and said third pivot to a secondposition on the opposite side of said line through said second pivot andsaid third pivot whereby said first brake engaging member and saidsecond brake engaging member are moved toward each other and said brakeleaves are allowed to move away from each other,

said lever being movable to a third position whereby said brakes arelocked.

26. The actuating mechanism recited in claim 25 wherein said supportcomprises a table structure,

a first anchor plate secured to a first end of said torsion rod and alsobeing secured to said drafting board and a lever secured to a second endof said torsion rod and to one of said legs whereby when said lock meansis released and said drafting board is moved toward a predeterminedposition, said torsion rod is rotatively twisted to counterbalance theweight of said drafting board.

1. In combination a locking mechanism for a drafting board, saiddrafting board being mounted on a support, a means to adjust said boardfor tilting on said support and means to adjust said board vertically onsaid support, said means to adjust said board for tilting comprisingfirst lock means to lock said drafting board on said support in selectedposition against tilting, second lock means to lock said drafting boardin selected vertical position, and a single handle connected to bothsaid locking means for actuating both said locking means by movement ofsaid handle, said first lock means and said second lock means beinglocked when said handle is in a first position, said first lock meansbeing unlocked and said second lock means being locked when said handleis moved to a second position, said first lock means being relocked andsaid second lock means being unlocked when said handle is in a thirdposition.
 2. The combination recited in claim 1 wherein said draftingboard is supported on a first leg and a second leg, transverse meansfixing said legs together at their upper ends, and counterbalance meansfor counterbalancing said drafting board in vertical position.
 3. Thecombination recited in claim 1 wherein said counterbalance meanscomprises an energy cell at one side of said drafting board, said energycell having an outer drum, a shaft and a spring connecting said shaft tosaid drum, and cable means connected to said legs and to said drum.
 4. Adrafting table comprising a support structure, a drafting board, firstmeans attaching said drafting board to said support structure fortilting, second means connecting said drafting board to said supportstructure for vertical movement whereby said drafting board can be movedup and down, first locking means to lock said drafting board againsttilting and second locking means to lock said drafting board againstvertical movement, and an actuating member connected to said firstlocking means and to said second lockIng means for actuating both saidlocking means locking said drafting board against tilting and againstvertical movement, said actuating member is movable to a first positionto lock said drafting board against both tilting and vertical movement,said actuating member is movable to a second position to unlock saidtilting movement and to lock said vertical movement and to a thirdposition to lock said drafting board against tilting and unlock saidboard for vertical movement.
 5. A drafting table comprising a supportingstructure, a pair of spaced legs comprising a yoke mounted for verticalmovement on said supporting structure, a drafting board, pivot means oneach said leg supporting said drafting board on said yoke, said firstlock means comprising two interleaved groups of brake plates, meanssecuring the plates of one of said groups of said plates to saiddrafting board, means securing the other plates of said group of saidplates to the upper end of one of said legs, a pivot tube extendingthrough said groups of brake plates, and actuating means for pressingsaid brake plates of both said groups together in tight frictionalengagement to hold said drafting board in selected pivotal positionrelative to said leg, said actuating means comprising a toggle linkage,including a first link and a second link, a third link attached to saidtoggle linkage, said third link having means thereon connected to anelevation lock to actuate a second lock means to lock said legs againstvertical movement, a torsion rod extending through said pivot tube, oneend of said torsion rod being fixed to said base, the other end of saidtorsion rod being fixed to said drafting board, said first lock meansand said second lock means being locked when said actuating means is ina first position, said first lock being unlocked and said second lockbeing locked when said actuating means is in a second position, saidfirst lock being relocked and said second lock being unlocked when saidactuating means is in a third position.
 6. The drafting board recited inclaim 5 wherein said yoke comprises a transverse member, a first leg anda second fixed to said transverse member, said legs being telescopicallyand slidably received in said base to raise and lower said board, anelevation lock means to lock said legs in selected elevated position,said actuating means comprising an angle bar in said transverse memberof said yoke, the outer ends of said transverse member being attached tosaid locking means, a pickup arm fixed to said bar, and means connectedto said links to engage said pickup arm to actuate said elevation lock.7. A drafting board comprising a support member, a first leg and asecond leg spaced from each other, said spaced legs slidably supportedon said support for vertical movement thereon, a drafting board, saiddrafting board being attached to an upper portion of said legs fortilting movement thereon, two spaced support angle members attached tothe lower side of said drafting board, one flange of each said supportangle extending generally perpendicular to said drafting board, twogroups of plates made up of a plurality of first brake plates and secondbrake plates disposed in parallel planes, one said group being disposedadjacent each said support angle, first spaced pins fixed to saidvertical flanges and extending through holes in said first brake plates,two second groups of brake plates made up of first brake plates andsecond brake plates, second pins fixed to said legs, said second pinsextending through holes in said second brake plates, a first bracketfixed to said first leg and a second bracket fixed to said second leg, atube extending through said brackets through said support angles andthrough both said first brake plates and through said second brakeplates whereby said drafting board is tiltably supported on said legs,said tube extending through said first plates and said second plates, afirst brake engaging member slidably supported on said tube and engagingsaid first brake plates, a second brake engaging member slidablysupported on said tube and engaging said second brake plates, a lever, afirst link having its first end pivoted to said lever at a first pivotpoint and having its second end pivoted to said first brake engagingmember, said lever being swingably attached at a third pivot point tosaid second brake engaging member, said first pivot point and saidsecond pivot point being spaced from each other, said lever beingadapted to be swung from a first position to a second position wherebysaid first brake engaging means and said second brake engaging means areforced away from each other and said first brake plates and said secondbrake plates are squeezed together locking said drafting board againsttilting, said lever being swingable to a second position where saidfirst pivot moves between said second pivot and said third pivot to asecond position on the opposite side of said line through said secondpivot and said third pivot whereby said first brake engaging member andsaid second brake engaging member are moved toward each other and saidbrake plates are allowed to move away from each other, said lever beingmovable to a third position, second locking means for locking saidcolumns in adjusted vertical positions, said second locking means havinga member engagable by second lock actuating means on said lever wherebysaid second locking means is actuated when said lever is moved to saidthird position.
 8. In combination, a drafting board and a support, firstmeans supporting said drafting board for tilting on said support, secondmeans supporting said drafting board for movement in elevation, firstlock means for locking said drafting board against tilting on saidsupport, second locking means for locking said drafting board againstmovement in elevation, actuating means for said first lock meanscomprising a first link, a second link pivotally connected to said firstlink forming a toggle linkage, said first link and said second linkbeing connected to said first lock means at their distal ends, a handleattached to said first link, a third link, having a first end and asecond end, said third link being connected to said first link at itssaid first end and connecting means connecting the said second end ofsaid third link to said second lock means, said third link beingconnected to said first link at a position between the connection ofsaid second link to said first link and said handle.
 9. The combinationrecited in claim 8 wherein said first locking means comprisesinterleaved plates at each side of said drafting board, and said firstlink and said second link are adapted to force said plates together infrictional engagement with each other.
 10. The combination recited inclaim 8 wherein said second locking means comprises two spaced verticalextending rods fixed to said support, two helical springs, one saidhelical spring disposed around each said rod, two rock plates rotatablysupported on said means supporting said drafting board for tilting, eachsaid helical spring having two ends, said two ends of each said springbeing fixed to one of said rock plates, said rock plates being connectedto said connecting means.
 11. The combination recited in claim 9 whereinsaid second locking means comprises two spaced vertical extending rodsfixed to said support, two helical springs, one said helical springdisposed around each said rod, two rock plates rotatably supported onsaid means supporting said drafting board for tilting, each said helicalspring having two ends, said two ends of each said spring being fixed toone of said rock plates, said rock plates being connected To saidconnecting means.
 12. The combination recited in claim 10 wherein saidconnecting means comprises two bell cranks fixed to said support,vertically extending means connecting said bell cranks to said rockplates, a pickup member connected to said bell cranks, and meansconnected to said third link adapted to engage said pickup member tomove said bell cranks and thereby move said rock levers to move saidhelical springs out of binding engagement with said rods.
 13. Thecombination recited in claim 12 wherein said means supporting saiddrafting board on said support comprises a tubular member supported onsaid support, said first lock means comprising a first tubular memberand a second tubular member telescopically supported on said tubularmember, said first and second tubular members comprising said first lockmeans and said second lock means, and a third tubular member slidablysupported on said second tubular member, said third tubular memberengaging said pickup member.
 14. The combination recited in claim 13wherein a compression spring is disposed in engagement with said rocklevers urging said rock levers to urge said helical springs to bind oneach said rod, said compression spring being adapted to exert a force onsaid third link when said lever is moved to a position to move saidfirst locking means toward each other whereby said first link and saidthird link co-act to lock said first locking means.
 15. In combination,a drafting board and a support with a locking mechanism for locking tworelatively swingable members together comprising two spaced firstmembers and two spaced second members, said first members being fixed toa drafting board, said second members being fixed to said support, afirst tubular member extending through said first members and saidsecond members swingably connecting said first members and said secondmembers together, a first group of brake leaves and a second group ofbrake leaves, said groups of brake leaves each being made up of aplurality of first brake leaves and second brake leaves, said firstbrake leaves being loosely received on spaced first pins on said firstmembers, said second brake leaves being loosely received on second pinson said second members, said tubular member extending through a hole ineach of said brake leaves thereby connecting said first brake leaves tosaid second brake leaves, a first square tube telescopically received onsaid first tubular member and disposed adjacent said first group ofbrake leaves, a second square tube telescopically received on said firsttubular member and disposed adjacent said second group of brake leaves,means on said first square tube engaging said first brake leaves, meanson said second square tube engaging said second brake leaves, a cranklink pivoted at one end to means on said first square tube, a first linkpivoted at one end to said second square tube and to said crank link,said crank link being swingable to urge said brake leaves together tohold said first brake leaves in frictional engagement with each other, athird square tube slidably supported on said second square tube, asecond link pivotably connected to said crank link at its first end andto said third square tube at its second end, said first link beingpivoted to said crank link between the pivotal connection of said cranklink to said second tube and the pivotal connection of said second link,said third square tube having means thereon adapted to engage a pickupmember, a handle fixed to said crank link, said handle being swingableto a first position urging said first square tube and said second squaretube from each other whereby said brake leaves of said first group andsaid brake leaves of said second group are each urged into frictionalengagement with each other, said handle being swingable to a secondposition whereby said leaves of said first group and said brake leAvesof said second group can each swing relative to the other, said handlebeing swingable to a third position whereby said second link forces saidthird square tube into engagement with said pickup member and a force isthereby exerted between said third tubular member and said first tubularmember forcing said brake leaves of said first tubular member intofrictional engagement.
 16. The combination recited in claim 15 wherein atorsion bar is telescopically received in said first tubular member,said torsion bar has a first end and a second end, said first end ofsaid torsion bar is fixed to said support, said second end of saidtorsion bar is fixed to said drafting board.
 17. The combination recitedin claim 16 wherein said second end of said torsion bar has adjustingmeans connecting it to said drafting board whereby the torsional forcecounterbalancing said drafting board may be adjusted.
 18. Thecombination recited in claim 17 wherein said support comprises a yokehaving a transverse member and two spaced vertically extending legs, adisk member slidably supporting said legs, a locking means for holdingsaid yoke in predetermined vertical position, a laterally extending baron said transverse member, a first bell crank and a second bell crankattached to each end of said transverse member, a locking member on eachsaid leg and attached to each said bell crank, said pickup member beingattached to said transverse bar.
 19. The drafting table recited in claim1 wherein said drafting board is attached to a yoke having a pair ofspaced legs mounted on said supporting structure, pivot means on eachsaid leg supporting said drafting board on said yoke, said means toadjust said board for tilting comprising a first group of brake platesand a second group of brake plates interleaved with said first group ofbrake plates, means securing the plates of said first group of saidplates to said drafting board, means securing the plates of said secondgroup of said plates to the upper end of one of said legs, a pivot tubeextending through said groups of brake plates, said handle comprisingactuating means for pressing said brake plates of both said groupstogether in tight frictional engagement with each other to hold saiddrafting board in selected pivotal position relative to said leg, saidactuating means further comprising a toggle linkage, including a firstlink swingably connected to means engaging said first group of platesand a second link swingably connected to means engaging said secondgroup of plates, and said first and said second links being swingablyconnected together and an actuating handle fixed to said first link, andmeans supporting said links to said pivot tube.
 20. The drafting boardrecited in claim 19 wherein a torsion rod extending through said pivottube, one end of said torsion rod being fixed to said yoke, the otherend of said torsion rod being fixed to said drafting board.
 21. Thedrafting board recited in claim 19 wherein said pivot means furthercomprises spaced platelike brackets on said yoke, one at each sidethereof, a first flange and a second flange spaced from each other andfixed to said board and disposed in planes generally parallel to saidbrackets, said first group of brake plates disposed ad-jacent said firstflange, said second group of brakes plates disposed adjacent said secondflange, said tube having a first end and a second end extending throughsaid brackets and through said flanges and through said first group ofbrake plates and through said second group of brake plates, said firstend of said tube having a nut thereon abutting the outside surface ofsaid first flange, the said second end of said tube being fixed to saidsecond flange.
 22. The drafting board recited in claim 21 wherein saidfirst flange has a first horizontal flange fixed thereto and said secondflange has A second horizontal flange fixed thereto, said horizontalflanges each having two laterally extending slots therein, fasteningmeans in said slots engaging said board holding said board to saidhorizontal flanges whereby said first and said second flanges may beadjusted toward and away from each other to adjust the outward movementof said brake leaves.
 23. The drafting board recited in claim 22 whereinsaid actuating means further comprises a first outside sleevetelescopically supported on said tube adjacent said first group of brakeleaves, a second outside sleeve telescopically supported on said tubeadjacent said second group of brake leaves, said means supporting saidfirst link and said second link on said pivot tube comprises said firstlink pivotally attached to said first outside sleeve, said second linkpivotally attached to said second outside sleeve, said links beingswingably connected together and handle means fixed to one said link.24. The drafting board recited in claim 21 wherein a torsion bar extendsthrough said first tube, said torsion bar having a first end and asecond end, means fixing a first end of said torsion bar againstrotation relative to said first flange, means fixing said second end ofsaid torsion bar against rotation relative to said second bracketwhereby said torsion bar is twisted when said board is tilted from ahorizontal position.
 25. The combination recited in claim 1 wherein saidmeans to adjust said board comprises a first leg and a second leg spacedfrom each other, said spaced legs slidably supported on said support forvertical movement thereon, said drafting board being attached to anupper portion of said legs for tilting movement thereon, a first supportangle and a second support angle spaced from each other and attached tothe lower side of said drafting board, one flange of each said supportangle extending generally perpendicular to said drafting board, a firstgroup of plates made up of a plurality of first brake plates and aplurality of second brake plates, a second group of brake plates made upof a plurality of third brake plates and a plurality of fourth brakeplates disposed in parallel planes, one said group being disposedadjacent each said support angle, first spaced pins fixed to saidvertical flanges and extending through holes in said first brake leaves,a first bracket fixed to said first leg and a second bracket fixed tosaid second leg, second pins fixed to said brackets, said second pinsextending through holes in said second brake leaves, a tube extendingthrough said brackets through said support angles and through both saidfirst brake leaves and through said second brake leaves whereby saiddrafting board is tiltably supported on said legs, a first brakeengaging member slidably supported on said tube and engaging said firstgroup of brake leaves, a second brake engaging member slidably supportedon said tube and engaging said second group of brake leaves, a lever, afirst link having its first end pivoted to said lever at a first pivotpoint and having its second end pivoted to said first brake engagingmember at a second pivot point, said lever being swingably attached at athird pivot point to said second brake engaging member, said first pivotpoint and said second pivot point being spaced from each other, saidlever being adapted to be swung from a first position to a secondposition whereby said first brake engaging means and said second brakeengaging means are forced away from each other and said first brakeleaves and said second brake leaves are squeezed together locking saiddrafting board against tilting, said lever being swingable to a secondposition where said first pivot moves between said second pivot and saidthird pivot to a second position on the opposite side of said linethrough said second pivot and said third pivot whereby said first brakeengaging member and said second brake engaging member are moved towardeach other and said brake leaves are allowed to move away from eachother, said lever being movable to a third position whereby said brakesare locked.
 26. The actuating mechanism recited in claim 25 wherein saidsupport comprises a table structure, a first anchor plate secured to afirst end of said torsion rod and also being secured to said draftingboard and a lever secured to a second end of said torsion rod and to oneof said legs whereby when said lock means is released and said draftingboard is moved toward a predetermined position, said torsion rod isrotatively twisted to counterbalance the weight of said drafting board.